My Arduino Micro and Arduino UNO detects as "Unknown device" in device managerI click update driver then I select my driver location "D:\arduino-1.0.2\drivers\FTDI USB Drivers" or "D:\arduino-1.0.2\drivers"after that I have this message:

I using Windows 8 purchased from Microsfot.please help.

I have been the exact seem thing you have been through ,but after I did what Louis wrote again ( idk if this is necessary ) I made the following steps :

1] right-Click on "My Computer"2]selected "Manage"3]after that clicked on "Device Manager"4]then Right Clicked on Your Arduino( From "unknown Devices" as I remember ^_^(probably you already know about all these previous steps , But ... )

5]after ,don't click on "update Driver Software" or whatever it was, but instead CLICK ON "Uninstall" .. it should disappear after that6]Plug out then re plug in your Arduino7]then do the "update driver software" thingy8]after that choose in the installing that 2sterednd option in that creepy red screen " install anyway" (I think you know this one too)

I really hope that this will work for as I have even registered in this forum just to post this help XD for you andthis random solution has worked for me today

Turning off the digital signatures for Win8 worked like a charm. I'd gotten Arduino Uno for my son for Christmas and was anxious to get it working. Thank you sooooo much for posting this solution. My son will be very happy!

Hi, I got an Arduino Uno yesterday and was trying to install the driver on Windows 8 64-bit. I got the same certificate message as everyone and after trying Louis' method, I was able to install the .inf through right-click>install. However the Arduino is still not recognized by the IDE. When going to Device Manager, the Arduino is listed as USB-Serial Controller under Other Devices (I know that's the Arduino because when I disconnect it, this device disappears).Any help would be greatly appreciated.

PS: When trying to "Update Driver Sodtware" from Device Manager and pointing to the drivers folder, I simply get :Windows could not find driver software for your device"

Related to this, I want to use my Mega 2560 as a slave device with a PC (in a Robot) with Windows 7 64 bit. The problem is that every time I reboot the PC, the Arduino is not recognized, unless I manually unplug and re-plug it in.

Anyone have any suggestion how to fix this? Obviously pressing F8 at each reboot is not an option.I want the Arduino to turn the PC off while it is "sleeping", and turn it on again to wake up... but it does not see the Arduino!